/* Copyright (C) 1999-2016 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
. */
#include "hurdlock.h"
#include
#include
#include
int lll_xwait (void *ptr, int lo, int hi, int flags)
{
return (__gsync_wait (__mach_task_self (),
(vm_offset_t)ptr, lo, hi, 0, flags | GSYNC_QUAD));
}
int lll_timed_wait (void *ptr, int val, int mlsec, int flags)
{
return (__gsync_wait (__mach_task_self (),
(vm_offset_t)ptr, val, 0, mlsec, flags | GSYNC_TIMED));
}
int lll_timed_xwait (void *ptr, int lo,
int hi, int mlsec, int flags)
{
return (__gsync_wait (__mach_task_self (), (vm_offset_t)ptr,
lo, hi, mlsec, flags | GSYNC_TIMED | GSYNC_QUAD));
}
/* Convert an absolute timeout in nanoseconds to a relative
* timeout in milliseconds. */
static inline int __attribute__ ((gnu_inline))
compute_reltime (const struct timespec *abstime, clockid_t clk)
{
struct timespec ts;
__clock_gettime (clk, &ts);
ts.tv_sec = abstime->tv_sec - ts.tv_sec;
ts.tv_nsec = abstime->tv_nsec - ts.tv_nsec;
if (ts.tv_nsec < 0)
{
--ts.tv_sec;
ts.tv_nsec += 1000000000;
}
return (ts.tv_sec < 0 ? -1 :
(int)(ts.tv_sec * 1000 + ts.tv_nsec / 1000000));
}
int __lll_abstimed_wait (void *ptr, int val,
const struct timespec *tsp, int flags, int clk)
{
int mlsec = compute_reltime (tsp, clk);
return (mlsec < 0 ? KERN_TIMEDOUT :
lll_timed_wait (ptr, val, mlsec, flags));
}
int __lll_abstimed_xwait (void *ptr, int lo, int hi,
const struct timespec *tsp, int flags, int clk)
{
int mlsec = compute_reltime (tsp, clk);
return (mlsec < 0 ? KERN_TIMEDOUT :
lll_timed_xwait (ptr, lo, hi, mlsec, flags));
}
int __lll_abstimed_lock (void *ptr,
const struct timespec *tsp, int flags, int clk)
{
if (lll_trylock (ptr) == 0)
return (0);
while (1)
{
if (atomic_exchange_acq ((int *)ptr, 2) == 0)
return (0);
else if (tsp->tv_nsec < 0 || tsp->tv_nsec >= 1000000000)
return (EINVAL);
int mlsec = compute_reltime (tsp, clk);
if (mlsec < 0 || lll_timed_wait (ptr,
2, mlsec, flags) == KERN_TIMEDOUT)
return (ETIMEDOUT);
}
}
void lll_set_wake (void *ptr, int val, int flags)
{
__gsync_wake (__mach_task_self (),
(vm_offset_t)ptr, val, flags | GSYNC_MUTATE);
}
void lll_requeue (void *src, void *dst, int wake_one, int flags)
{
__gsync_requeue (__mach_task_self (), (vm_offset_t)src,
(vm_offset_t)dst, (boolean_t)wake_one, flags);
}
/* Robust locks. */
extern int __getpid (void) __attribute__ ((const));
extern task_t __pid2task (int);
/* Test if a given process id is still valid. */
static inline int valid_pid (int pid)
{
task_t task = __pid2task (pid);
if (task == MACH_PORT_NULL)
return (0);
__mach_port_deallocate (__mach_task_self (), task);
return (1);
}
/* Robust locks have currently no support from the kernel; they
* are simply implemented with periodic polling. When sleeping, the
* maximum blocking time is determined by this constant. */
#define MAX_WAIT_TIME 1500
int lll_robust_lock (void *ptr, int flags)
{
int *iptr = (int *)ptr;
int id = __getpid ();
int wait_time = 25;
unsigned int val;
/* Try to set the lock word to our PID if it's clear. Otherwise,
* mark it as having waiters. */
while (1)
{
val = *iptr;
if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
return (0);
else if (atomic_compare_and_exchange_bool_acq (iptr,
val | LLL_WAITERS, val) == 0)
break;
}
for (id |= LLL_WAITERS ; ; )
{
val = *iptr;
if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
return (0);
else if (val && !valid_pid (val & LLL_OWNER_MASK))
{
if (atomic_compare_and_exchange_bool_acq (iptr, id, val) == 0)
return (EOWNERDEAD);
}
else
{
lll_timed_wait (iptr, val, wait_time, flags);
if (wait_time < MAX_WAIT_TIME)
wait_time <<= 1;
}
}
}
int __lll_robust_abstimed_lock (void *ptr,
const struct timespec *tsp, int flags, int clk)
{
int *iptr = (int *)ptr;
int id = __getpid ();
int wait_time = 25;
unsigned int val;
while (1)
{
val = *iptr;
if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
return (0);
else if (atomic_compare_and_exchange_bool_acq (iptr,
val | LLL_WAITERS, val) == 0)
break;
}
for (id |= LLL_WAITERS ; ; )
{
val = *iptr;
if (!val && atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
return (0);
else if (val && !valid_pid (val & LLL_OWNER_MASK))
{
if (atomic_compare_and_exchange_bool_acq (iptr, id, val) == 0)
return (EOWNERDEAD);
}
else
{
int mlsec = compute_reltime (tsp, clk);
if (mlsec < 0)
return (ETIMEDOUT);
else if (mlsec > wait_time)
mlsec = wait_time;
int res = lll_timed_wait (iptr, val, mlsec, flags);
if (res == KERN_TIMEDOUT)
return (ETIMEDOUT);
else if (wait_time < MAX_WAIT_TIME)
wait_time <<= 1;
}
}
}
int lll_robust_trylock (void *ptr)
{
int *iptr = (int *)ptr;
int id = __getpid ();
unsigned int val = *iptr;
if (!val)
{
if (atomic_compare_and_exchange_bool_acq (iptr, id, 0) == 0)
return (0);
}
else if (!valid_pid (val & LLL_OWNER_MASK) &&
atomic_compare_and_exchange_bool_acq (iptr, id, val) == 0)
return (EOWNERDEAD);
return (EBUSY);
}
void lll_robust_unlock (void *ptr, int flags)
{
unsigned int val = atomic_load_relaxed((unsigned int *)ptr);
while (1)
{
if (val & LLL_WAITERS)
{
lll_set_wake (ptr, 0, flags);
break;
}
else if (atomic_compare_exchange_weak_release ((unsigned int *)ptr, &val, 0))
break;
}
}